Lofting along a path
I'm all about the nodes too, but i'm also all about leveraging the power of Blender from inside Sverchok. (When it makes sense, and when it can offer perfomance boosts.) This also offloads the pesky "twist" Matrix calculations to Blender, and lets you use the Twist parameter on the Trajectory curves.

For now i started a discussion about this on our Issue tracker, because I think this technique can be wrapped into a single node and automated/parametrized.

What I did here was generate two Profiles using generator nodes (Ngon, and Circle) and output them using the PolyLine Viewer, i also made sure the profiles had the same vertex count and the vertex positions aligned to allow nice linear interpolation between the two shapes. Then I added a trajectory and copied it, and added the two bevel shapes to them individually 

 

then the Objects In node imports both Curve Objects as Meshes, we separate the two meshes, and divide each mesh by the number of vertices of the Profile vertex count. This division results in a number which corresponds to the number of nodes/vertices in the original trajectory Curves. It also is the number of times we need to repeat each element of our interpolation range. so we go from

[0.0, 0.07, ....1.0]


to

[  0.0,  0.0,  0.0,  0.0,  ...
   0.07, 0.07, 0.07, 0.07, ...
   ...   ...   ...   ...   ...
   ...   1.0,  1.0,  1.0,  1.0  ]


We do that with the List Repeat node, and List "Delete Levels" (which is essentially a "Flatten List" node)

here's the blend